(aux_item_add_perm): Removed the arguments item_creator,
	object_creator and owner_check.  Added the arguments
	creating_conn and subordinate.  All callers updated.
	Simplified the code.  Use is_supervisor() instead of
	is_strictly_supervisor() where appropriate.  Use the supplied
	connection instead of checking that ACTPERS is the
	item_creator.  Adjusted for the new contents of
	Aux_item_validation_data.
(aux_inherit_items): Removed arguments target_creator, creating and
	object_type.  Added argument subordinate.  Changed type of
	arguments object_no and object, since we know that they are a
	Text_no and Text_stat, respectively.
(filter_aux_item_list): Assert that the viewer_conn argument is
	non-NULL.
(check_delete_aux_item_list): Renamed the "owner" argument
	"subordinate".
(text_stat_check_add_aux_item_list): Removed the item_creator and
	creating arguments.  Added the creating_conn argument, and
	assert it is non-NULL.
(conf_stat_check_add_aux_item_list): Replaced the "creator" argument
	with "creating_conn".  Argument assertions added.
(system_check_add_aux_item_list): Ditto.
(aux_item_validate_existing_text): Changed return type from Bool to
	Success.  Use person_text_read_access() only when necessary,
	and add a comment explaining why it might happen.